In 1619 Johannes Kepler published his Third Law of Planetary Motion which describes the relationship between the orbital periods of the planets and their distance from the Sun.

The square of the orbital period equals
the cube of the orbital semi-major axis.

Kepler’s Third Law clearly defines the spiral [vortex] nature of the Solar System.

However, it wasn’t until the Voyager 1 satellite left the Solar System in 2012 that:
1) The outer boundary of the Solar System could be established.
2) The rotation period of the Solar System could be calculated.

The Voyager 1 spacecraft is a 722 kilogram (1,592 lb) space probe launched by NASA on September 5, 1977 to study the outer Solar System and interstellar medium. Operating for 35 years, 1 month and 23 days as of 28 October 2012, the spacecraft receives routine commands and transmits data back to the Deep Space Network.

At a distance of about 122 AU (1.83×1010 km) as of September 2012, it is the furthest manmade object from Earth. Voyager 1 is now in the heliosheath, which is the outermost layer of the heliosphere. On June 15, 2012, NASA scientists reported that Voyager 1 may be very close to entering interstellar space and becoming the first manmade object to leave the Solar System.

Kepler’s Third Law indicates that the outer boundary of the Solar System [at 122 AU] rotates around the Sun with a period of 1,347.534 years.

However, using modern astronomical measurements Excel calculates a slightly more precise rotation period for the outer boundary for the Solar System of 1,350 years.

With the outer boundary established and the rotational period calculated it is now possible to define the overall shape of the Solar System Rankine Vortex:

The inner core of a Rankine Vortex is a solid-like rotational “forced vortex”.
Therefore, it is likely that the Sun has a solid core hidden beneath its photosphere.

The outer circulatory spiral of the planetary disc is an irrotational “free vortex” which generates a centripetal force [which is commonly known as “gravity”] that will primarily sequence the planetary disc based upon planetary density.

The centripetal force is weak at the outer boundary of the Solar System at 122 AU.
Therefore, 122 AU marks the boundary where the “gravity” of the Solar System becomes primarily a circular vector associated with it’s 1,350 year rotation period.